Temperate forests are under increasing stress from rising temperatures and increasingly variable precipitation. Traditionally, tree species have been assumed to have two options to respond to climate change – range shifts through space to track historical climates, or adaptation in place to tolerate novel climates. Since plants rely on microbial partnerships for a suite of essential processes, including nutrient acquisition and drought tolerance, we tested a possible third option – can trees gain tolerance to novel climates by changing their associations with microbial partners in their roots? In two parallel field experiments in northern Wisconsin and central Illinois, we tested whether inoculating tree seedlings with microbial communities sourced from sites within each state varying in precipitation and temperature could affect seedling survivorship in ambient and rainfall-reduced plots.
Results/Conclusions
In the first year of the study, we found that inoculating tree seedlings with microbial communities sourced from warmer and/or drier locations could promote seedling survival in rainfall-reduced plots in some cases. These results were stronger in the hotter central Illinois site, while in the cooler Wisconsin site seedling survivorship was generally reduced by inoculation with foreign microbial communities. We have characterized the fungal and bacterial communities in each inoculated community using metabarcoding of ITS and 16S genes, and will use this data to investigate aspects of microbial communities predictive of enhanced seedling survival in the field experiment. These results suggest that movement of microbial taxa, whether via natural spread or pre-inoculation of seedlings in forestry plantings, may provide an additional avenue to enhance climate resilience of tree populations.